diff --git a/pkg/sound/sound.go b/pkg/sound/sound.go
new file mode 100644
index 000000000..7b5a23ffe
--- /dev/null
+++ b/pkg/sound/sound.go
@@ -0,0 +1,85 @@
+// Package sound provides cross-platform sound notification support.
+// It plays system sounds asynchronously to notify users of task completion or failure.
+package sound
+
+import (
+	"log/slog"
+	"os/exec"
+	"runtime"
+)
+
+// Event represents the type of sound to play.
+type Event int
+
+const (
+	// Success is played when a task completes successfully.
+	Success Event = iota
+	// Failure is played when a task fails.
+	Failure
+)
+
+// Play plays a notification sound for the given event in the background.
+// It is non-blocking and safe to call from any goroutine.
+// If the sound cannot be played, the error is logged and silently ignored.
+func Play(event Event) {
+	go func() {
+		if err := playSound(event); err != nil {
+			slog.Debug("Failed to play sound", "event", event, "error", err)
+		}
+	}()
+}
+
+func playSound(event Event) error {
+	switch runtime.GOOS {
+	case "darwin":
+		return playDarwin(event)
+	case "linux":
+		return playLinux(event)
+	case "windows":
+		return playWindows(event)
+	default:
+		return nil
+	}
+}
+
+func playDarwin(event Event) error {
+	// Use macOS built-in system sounds via afplay
+	var soundFile string
+	switch event {
+	case Success:
+		soundFile = "/System/Library/Sounds/Glass.aiff"
+	case Failure:
+		soundFile = "/System/Library/Sounds/Basso.aiff"
+	}
+	return exec.Command("afplay", soundFile).Run()
+}
+
+func playLinux(event Event) error {
+	// Try paplay (PulseAudio) first, then fall back to terminal bell
+	var soundFile string
+	switch event {
+	case Success:
+		soundFile = "/usr/share/sounds/freedesktop/stereo/complete.oga"
+	case Failure:
+		soundFile = "/usr/share/sounds/freedesktop/stereo/dialog-error.oga"
+	}
+
+	if path, err := exec.LookPath("paplay"); err == nil {
+		return exec.Command(path, soundFile).Run()
+	}
+
+	// Fallback: terminal bell via printf
+	return exec.Command("printf", `\a`).Run()
+}
+
+func playWindows(event Event) error {
+	// Use PowerShell to play system sounds
+	var script string
+	switch event {
+	case Success:
+		script = `[System.Media.SystemSounds]::Asterisk.Play()`
+	case Failure:
+		script = `[System.Media.SystemSounds]::Hand.Play()`
+	}
+	return exec.Command("powershell", "-NoProfile", "-NonInteractive", "-Command", script).Run()
+}
diff --git a/pkg/tui/page/chat/chat.go b/pkg/tui/page/chat/chat.go
index 75a730d01..3970c59fa 100644
--- a/pkg/tui/page/chat/chat.go
+++ b/pkg/tui/page/chat/chat.go
@@ -8,6 +8,7 @@ import (
 	"path/filepath"
 	goruntime "runtime"
 	"strings"
+	"time"
 
 	"charm.land/bubbles/v2/help"
 	"charm.land/bubbles/v2/key"
@@ -144,6 +145,7 @@ type chatPage struct {
 	msgCancel       context.CancelFunc
 	streamCancelled bool
 	streamDepth     int // nesting depth of active streams (incremented on StreamStarted, decremented on StreamStopped)
+	streamStartTime time.Time
 
 	// Track whether we've received content from an assistant response
 	// Used by --exit-after-response to ensure we don't exit before receiving content
diff --git a/pkg/tui/page/chat/runtime_events.go b/pkg/tui/page/chat/runtime_events.go
index ec3d99b44..f9787bcf1 100644
--- a/pkg/tui/page/chat/runtime_events.go
+++ b/pkg/tui/page/chat/runtime_events.go
@@ -8,12 +8,14 @@ import (
 	tea "charm.land/bubbletea/v2"
 
 	"github.com/docker/docker-agent/pkg/runtime"
+	"github.com/docker/docker-agent/pkg/sound"
 	"github.com/docker/docker-agent/pkg/tui/components/notification"
 	"github.com/docker/docker-agent/pkg/tui/components/sidebar"
 	"github.com/docker/docker-agent/pkg/tui/core"
 	"github.com/docker/docker-agent/pkg/tui/dialog"
 	msgtypes "github.com/docker/docker-agent/pkg/tui/messages"
 	"github.com/docker/docker-agent/pkg/tui/types"
+	"github.com/docker/docker-agent/pkg/userconfig"
 )
 
 // Runtime Event Handling
@@ -51,6 +53,9 @@ func (p *chatPage) handleRuntimeEvent(msg tea.Msg) (bool, tea.Cmd) {
 	switch msg := msg.(type) {
 	// ===== Error and Warning Events =====
 	case *runtime.ErrorEvent:
+		if userconfig.Get().GetSound() {
+			sound.Play(sound.Failure)
+		}
 		return true, p.messages.AddErrorMessage(msg.Error)
 
 	case *runtime.WarningEvent:
@@ -191,6 +196,7 @@ func (p *chatPage) handleStreamStarted(msg *runtime.StreamStartedEvent) tea.Cmd
 	slog.Debug("handleStreamStarted called", "agent", msg.AgentName, "session_id", msg.SessionID)
 	p.streamCancelled = false
 	p.streamDepth++
+	p.streamStartTime = time.Now()
 	spinnerCmd := p.setWorking(true)
 	pendingCmd := p.setPendingResponse(true)
 	sidebarCmd := p.forwardToSidebar(msg)
@@ -239,6 +245,13 @@ func (p *chatPage) handleStreamStopped(msg *runtime.StreamStoppedEvent) tea.Cmd
 	}
 
 	// Outermost stream stopped — fully clean up.
+	if userconfig.Get().GetSound() {
+		duration := time.Since(p.streamStartTime)
+		threshold := time.Duration(userconfig.Get().GetSoundThreshold()) * time.Second
+		if duration >= threshold {
+			sound.Play(sound.Success)
+		}
+	}
 	p.msgCancel = nil
 	p.streamCancelled = false
 	spinnerCmd := p.setWorking(false)
diff --git a/pkg/userconfig/userconfig.go b/pkg/userconfig/userconfig.go
index 81ecead0e..167d23cf4 100644
--- a/pkg/userconfig/userconfig.go
+++ b/pkg/userconfig/userconfig.go
@@ -55,11 +55,20 @@ type Settings struct {
 	// RestoreTabs restores previously open tabs when launching the TUI.
 	// Defaults to false when not set (user must explicitly opt-in).
 	RestoreTabs *bool `yaml:"restore_tabs,omitempty"`
+	// Sound enables playing notification sounds on task success or failure.
+	// Defaults to false when not set (user must explicitly opt-in).
+	Sound *bool `yaml:"sound,omitempty"`
+	// SoundThreshold is the minimum duration in seconds a task must run
+	// before a success sound is played. Defaults to 5 seconds.
+	SoundThreshold int `yaml:"sound_threshold,omitempty"`
 }
 
 // DefaultTabTitleMaxLength is the default maximum tab title length when not configured.
 const DefaultTabTitleMaxLength = 20
 
+// DefaultSoundThreshold is the default duration threshold for sound notifications.
+const DefaultSoundThreshold = 10
+
 // GetTabTitleMaxLength returns the configured tab title max length, falling back to the default.
 func (s *Settings) GetTabTitleMaxLength() int {
 	if s == nil || s.TabTitleMaxLength <= 0 {
@@ -68,6 +77,22 @@ func (s *Settings) GetTabTitleMaxLength() int {
 	return s.TabTitleMaxLength
 }
 
+// GetSound returns whether sound notifications are enabled, defaulting to true.
+func (s *Settings) GetSound() bool {
+	if s == nil || s.Sound == nil {
+		return true
+	}
+	return *s.Sound
+}
+
+// GetSoundThreshold returns the minimum duration for sound notifications, defaulting to 5s.
+func (s *Settings) GetSoundThreshold() int {
+	if s == nil || s.SoundThreshold <= 0 {
+		return DefaultSoundThreshold
+	}
+	return s.SoundThreshold
+}
+
 // GetSplitDiffView returns whether split diff view is enabled, defaulting to true.
 func (s *Settings) GetSplitDiffView() bool {
 	if s == nil || s.SplitDiffView == nil {